Cloud-seeding by Chinese meteorologists has led to the earliest snow blizzard in Beijing for two decades.

The 11-hour snowfall, which could be the heaviest in a decade, brought the capital to a halt and hundreds of flights were delayed.

China’s meteorologists are desperate to alleviate a prolonged drought gripping swaths of the country. Zhang Qiang, head of the Beijing Weather Modification Office, said: "We won’t miss any opportunity of artificial precipitation since Beijing is suffering from a lingering drought."

With forecasts for precipitation and a sharp drop in temperatures at the weekend, the meteorologists saw their chance. From 8pm on Saturday they fired 186 silver iodide capsules into clouds heavy with snow to help the precipitation. The result was snow that fell for 11 hours from the early hours of Sunday until mid-afternoon.

The cloud-seeding expanded the natural snowfall by 16 million tonnes, officials said. It was not clear how they calculated that figure. Beijing is becoming increasingly sophisticated in the use of cloud-seeding. Officials fired off 1,110 silver iodide rockets before the Olympic Games opening ceremony on August 8 last year to ensure clear skies on the night.

On Coal Hill, a scenic spot in the heart of Beijing that overlooks the Forbidden City, officials reported 25mm (0.9in) of snow. Temperatures plummeted by as much as 20C from Saturday to a low of about minus 9C late on Sunday as the clouds cleared and winds blew over the city from Siberia.

Snow has not fallen so early in the season in Beijing since 1987, officials said. The earliest recorded snowfall in the city was on October 26, 1960. Beijing is accustomed to freezing winters but snow rarely falls more than three or four times each winter.

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